Air bag module with variable inflation

ABSTRACT

An air bag module includes an air bag and an inflator being activatable to discharge inflator gas for inflating the air bag. The inflator has at least one discharge port through which inflator gas is discharged. A housing includes at least one inflator vent opening aligned with the discharge port. A variable inflation device is mounted on the inflator and includes a movable member alignable with the vent opening. The movable member is movable relative to the vent opening for opening and closing the vent opening at a predetermined time during inflator activation to control the amount of inflator gas discharged into the air bag and the amount of inflator gas expelled out through the vent opening of the housing. Preferably, the variable inflation device includes an initiator device being activatable during activation of the inflator to move the movable member relative to the vent opening at the predetermined time during inflator activation.

This is a divisional of application Ser. No. 09/075,731 filed on May 11,1998 now U.S. Pat. No. 6,123,358.

TECHNICAL FIELD

This invention relates to an air bag module capable of variable air baginflation.

BACKGROUND OF THE INVENTION

It is well known in the prior art to provide an air bag module whichincludes an inflatable air bag for protection of a vehicle occupant. Theair bag module typically includes an inflator for discharging inflatorgas to inflate the air bag. Upon sensing certain predetermined vehicleconditions, such as a certain amount of vehicle deceleration, theinflator discharges a fixed amount of inflator gas and the air bag isdeployed.

In some cases, it may be desirable to provide an inflator that hasvaried levels or stages of inflator gas output in response to thesensing of different vehicle or occupant conditions. Thus, it is alsoknown in the prior art to provide a dual-stage inflator that candischarge predetermined amounts of gas at one or two levels. However,these dual-stage inflators are more complex than typical inflators andhave the limitation of typically providing only two different levels ofgas output. An inflator that discharges inflator gas at a wide range oflevels is not readily available. Even if available, dual-stage ormulti-stage inflators are complex to manufacture and add mass to the airbag module.

It has also been suggested in the prior art to provide an air bag moduleincluding a reaction canister which houses the inflator and air bag andwhich includes a valve member which is continually repositioned foropening, closing, or partially opening the vent openings on the reactioncanister primarily in response to changes in ambient temperature by theuse of a bimetallic spring, servo motor or solenoid valve. Thus, theamount of the discharging inflator gas expelled from the housing iscontrolled solely by the exact position of the valve member which mustbe carefully positioned for providing partial opening of the ventopenings. In addition, the prior art teaches that the position of thevalve member and the amount of venting is continually adjusted duringvehicle use prior to activation of the inflator rather than onlyspecifically at the time of air bag deployment. In addition, the use ofa bimetallic spring, servomotor or solenoid takes time to move the valvemember between the various positions and thus is continually beingadjusted prior to activation of the inflator. This arrangement is alsocomplex and adds mass to the module.

SUMMARY OF THE INVENTION

This invention provides advantages and alternatives over the prior artby providing a variable inflation device that provides a wide range oflevels of inflator gas into the air bag. This can be accomplished withan inflator having a single output level for discharging inflator gas.Advantageously, this invention provides a lightweight device mounted onthe inflator which can be activated nearly instantaneously to vary theamount of venting for the module and thus the level of inflator gasdischarged into the air bag based upon occupant and vehicle conditions.Thus, the device need only be activated under circumstances in which theinflator is activated and not on a continual basis prior to inflatoractivation. Preferably, the level of inflator gas discharged into theair bag is varied based on the exact time that a vent opening in thehousing is either opened or closed during inflator activation.Advantageously, the device may be expendable since it is only used once,if at all, during inflator activation. Furthermore, the device iscompact and is mounted externally on the inflator such that the variableinflation device serves the dual purpose of attaching the inflator tothe housing in addition to providing variable inflation. Furthermore,other than vent holes, the variable inflation device requires nomodifications to the housing and is not limited by the shape of thehousing. In addition, the variable inflation device may be used withtraditional single stage inflators without internal modifications to theinflator.

These advantages are accomplished in the present invention by providingan air bag module for restraint of an occupant in a vehicle. The moduleincludes an air bag -and an inflator being activatable to dischargeinflator gas for inflating the air bag. The inflator has at least onedischarge port through which inflator gas is discharged. A housingincludes at least one inflator vent opening aligned with the dischargeport. A variable inflation device is mounted on the inflator andincludes a movable member alignable with the vent opening. The movablemember is movable relative to the vent opening for opening and closingthe vent opening at a predetermined time during inflator activation tocontrol the amount of inflator gas discharged into the air bag and theamount of inflator gas expelled out through the vent opening of thehousing. Preferably, the variable inflation device includes an initiatordevice being activatable during activation of the inflator to move themovable member relative to the vent opening at the predetermined timeduring inflator activation.

Thus, it will be appreciated that variable levels of inflation of theair bag can be achieved using a single inflator having only a singlelevel of gas output in combination with at least one vent opening thatis preferably either entirely opened or entirely closed at apredetermined time during discharge of inflator gas by a movable memberin response to activation of the initiator device. Almost instantaneouscontrol of the movable member is enabled by the use of the initiatordevice that reacts nearly instantaneously to the signal received fromthe vehicle sensors. It will also be appreciated that this systemprovides a relatively simple, cost effective, and lightweight solutionto providing variable levels of air bag inflation from a single levelinflator.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is an exploded perspective view showing a passenger side air bagmodule including an inflator having a movable member for closing a ventopening in the housing, but not showing the air bag;

FIG. 2 is a top assembled view of the air bag module of FIG. 1;

FIG. 3 is a sectional view taken generally along line 3—3 of FIG. 4 andshowing the movable member in a first position in solid lines and in asecond position in phantom lines, and including the air bag;

FIG. 4 is a top view of the variable inflation device assembly withoutthe housing and air bag;

FIG. 5 is a top assembled view similar to FIG. 4, but showing analternate embodiment of the invention;

FIG. 6 is a sectional view taken generally along line 6—6 of FIG. 5, butincluding the housing and air bag;

FIG. 7 is an exemplary graph depicting percent of maximum inflatoroutput delivered to the air bag versus time for the case in which thevent opening is normally open and is closed at a predetermined timeincrement by the variable inflation device; and

FIG. 8 is a side sectional view similar to FIG. 3, but showing anotheralternate embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-3, an air bag module 10 is mounted in a vehicle(not shown) for protection of a vehicle occupant (not shown). The module10 includes a housing 20, an inflatable air bag 27, and an inflator 30for generating gas to inflate the air bag 27. The module 10 is typicallymounted on the passenger side of the vehicle, but could also be mountedin other locations on the vehicle. The module 10 is secured to thevehicle in any suitable manner. The module 10 further includes avariable inflation device 49 which is externally mounted on the inflator30 to provide the variable inflation device. The variable inflationdevice 49 is used to vary the amount of inflator gas available for airbag inflation and mount the inflator 30 to the housing 20, as describedin detail hereinafter.

The housing 20 includes opposing sides walls 14, 15 joined by a bottomwall 16 and opposing end walls 17, 18. As best shown in FIGS. 1 and 3,the end wall 17 includes an enlarged first end opening 22 for receivingthe inflator 30 and variable inflation device 49 therethrough duringassembly. In addition, the other end wall 18 preferably includes asecond end opening 23 which is smaller than the first end opening 22 formounting the components of the variable inflation device 49. The sidewalls 14, 15 and end walls 17, 18 cooperatively define a housing opening19 through which the air bag 27 is deployed. The housing 20 furtherincludes one or more direct inflator vent openings 21 which arepreferably positioned in the bottom wall 16 of the inflator 30 and whichare directly aligned with specific predetermined discharge ports 31 inthe bottom of the inflator 30. The direct inflator vent opening 21 ispreferably in the shape of an elongated slot. One or more connectorstrips (not shown) may extend across the direct inflator vent opening 21to prevent the bottom wall 16 surrounding the relatively large directinflator vent opening 21 from deforming during the discharge ofinflation gas. The housing 20 may also include a plurality of side ventopenings 24 in the side walls 14, 15 which are not aligned with thedischarge ports 31, and which may be used for air bag deflation duringride down after full air bag deployment, as is well known in motorvehicles.

As best shown in FIG. 1, the inflator 30 may be of any conventionalconstruction for generating inflator gas to inflate the air bag 27.Advantageously, the inflator 30 is preferably a single stage inflator 30which outputs inflator gas at a single level for inflating the air bag27. The inflator 30 has a generally cylindrical body portion 36 and isinsertable through the first end opening 22 in the end wall 17 forinsertion within the housing 20. The inflator 30 also includes aplurality of discharge ports 31 which are preferably circumferentiallyspaced around a diffuser portion 33 of the inflator 30. Preferably,certain predetermined discharge ports 31 are generally in directalignment with the corresponding direct inflator vent openings 21 in thebottom wall 16 of the housing 20. The inflator 30 includes a first end34 and an opposite second end 35 on which the diffuser portion 33 islocated. The second end 35 of the inflator 30 includes a generally flathead portion 32 onto which the variable inflation device 49 can beattached, as described further hereinafter. The first end 34 of theinflator 30 is seated in the first end opening 22 of the housing 20 andis preferably surrounded by a grommet 25 for preventing vibration. Thesecond end 35 of the inflator 30 is operatively connected to the housing20 by the variable inflation device 49, as described furtherhereinafter.

The air bag 27 may be of any conventional construction for inflatingupon the discharge of inflator gas. Referring to FIG. 3, the air bag 27is stored in a folded condition atop the inflator 30 prior to inflatoractivation. Upon activation of the inflator 30, the air bag 27 is filledwith a predetermined amount of inflator gas as dictated by the variableinflation device 49 and deploys out through the housing opening 19 forprotection of the vehicle occupant. A cushion retainer 28 sewn into amouth portion 29 of the air bag 27 may be utilized to attach the air bag27 to a rim portion 26 of the housing 20. However, it will beappreciated that many other air bag 27 attachment methods are possible.

As best shown in FIG. 1, the variable inflation device 49 includes aplunger 70, a support member 88, a movable member 50, a cap nut 60, andan initiator device 80. The support member 88 preferably has a hollowtubular shape. The support member 88 includes interior walls 95 definingan axial opening 89 into which the plunger 70 and the initiator device80 can be inserted during assembly. The support member 88 includes afirst support end 90 preferably having a flange 91 that is secureddirectly to the head portion 32 of the diffuser portion 33 of theinflator 30 at the second end 35. The flange 91 may be secured by anysuitable method, such as welding, and the support member 88 ispreferably made of a metallic material. The support member 88 alsoincludes a spacing shoulder 92 which is sized larger than the second endopening 23 of the housing 20 so that the support member 88 is limitedfrom going through the second opening 23 and is properly positionedwithin the housing 20 during assembly. The spacing shoulder 92 ispreferably integrally formed with the support member 88, such as bydimpling or molding, but may also be provided as a separate pieceattached to or slipped over the support member 88, as will be describedfurther hereinafter in the alternate embodiment of FIGS. 5 and 6. In theinstalled condition, the spacing shoulder 92 abuts the end wall 18 ofthe housing 20, as best shown in FIGS. 2 and 3.

Preferably, the support member 88 is externally attached to the inflator30 and may be provided as an assembly with the inflator 30 or mayalternately be integrally formed with the inflator 30. Advantageously,the variable inflation device 49 may be used without any internalmodifications to the inflator 30. As best shown in FIG. 2, the supportmember 88 includes upper and lower guide holes 93, 94 that arevertically aligned with each other. The upper and lower guide holes 93,94 are axially elongated along the length of the support member 88 suchthat the movable member 50 may be moved along the length of the guideholes 93, 94 upon actuation of the variable inflation device 49. Themovable member 50 is vertically inserted through the guide holes 93, 94and the plunger 70 during assembly such that the movable member 50 iscoupled to the plunger 70 and guided by the guide holes 93, 94, asdescribed further hereinafter. The support member 88 further includes athreaded end portion 96 extending past the spaced shoulder 92 and spacedaxially away from the inflator 30 to extend out through the second endopening 23 of the housing 20 for mating with the cap nut 60 to securethe inflator 30 and variable inflation device 49 to the housing 20. Asbest shown in FIG. 1, the support member 88 may include a notchedorientation feature 97 for proper positioning of the support member 88relative to the housing 20 and for proper positioning of the upper andlower guide holes 93, 94.

The variable inflation device 49 further includes a plunger 70 which ispreferably integrally formed from a plastic material and has a generallycylindrical shape. The plunger 70 is seated inside the support member 88and has a diameter which is slightly smaller than the diameter of theaxial opening 89 such that the plunger 70 is slidable relative to theinterior walls 95 of the support member 88. The plunger 70 includes aradial plunger hole 71 which is sized for close receipt of the movablemember 50 therethrough, such as by snap-fitted attachment. It will beappreciated that other methods of attaching the movable member 50 to theplunger 70 may also be used, such as crimping, fastening, or adhesion.The plunger 70 includes a shear feature 72 that is shown as a flangelocated at an end of the plunger 70. The shear feature 72 is preferablyintegrally formed with the plunger 70, but may also be a separate pieceattached to the plunger 70. The shear feature 72 is sized larger thanthe axial opening 89 of the support member 88 such that the shearfeature 72 engages the support member 88 during insertion to limit theinsertion of the plunger 70 into the support member 88. In addition, themovable member 50 coupled to the plunger 70 is properly positioned inthe module 10 by the shear feature 72. Upon activation of the initiatordevice 80, the shear feature 72 breaks off and permits the plunger 70 toslide within the support member 88 until engaging the head portion 32 ofthe inflator 30 which acts as a stop surface. The plunger 70 alsopreferably includes an axial plunger bore 73 in which the initiatordevice 80 is seated prior to activation. A reaction surface 74 of theplunger 70 is located in the bottom of the axial bore 73. The plunger 70may also include a notched plunger orientation feature 75 for properalignment of the plunger bole 71 for assembly.

As best shown in FIG. 1, the movable member 50 includes an upwardlyprojecting arm portion 51 and a slide portion 52 extending generally ata right angle to the arm portion 51. The arm portion 51 preferablyincludes snap features 53 which enable the arm portion 51 to besnap-fittedly attached within the plunger hole 71. However, it will beappreciated that the arm portion 51 could be attached to the plunger 70by any suitable method. The slide portion 52 has a generally curvedshape that allows the movable member 50 to fit through the first endopening 22 of the housing 20 during assembly and also may be generallyshaped like the contour of the bottom wall 16 of the housing 20. Themovable member 50 also may include rib portions 54 that preventdeflection of the slide portion 52 during air bag inflation. However, itwill also be appreciated that it may be advantageous to allow the curvedslide portion 52 to deflect in the closed position to the shape of thebottom wall 16 of the housing 20 for better sealing of the directinflator vent opening 21. The movable member 50 is movable relative tothe inflator vent opening 21 for opening and closing the inflator ventopening 21 at a predetermined time to control the amount of inflator gasdischarged into the air bag 27 and the amount of inflator gas expelledout through the inflator vent opening 21 of the housing 20 so as not tobe available for air bag inflation. The slide portion 52 of the movablemember 50 is positionable adjacent to the inflator vent opening 21, andpreferably the slide portion 52 is sized equal to or greater than theinflator vent opening 21. Referring to FIGS. 1-3, the movable member 50is shown in a first position in solid lines in which the inflator ventopening 21 is open for lowering the amount of gas available for air baginflation. FIG. 3 shows the slide portion 52 in phantom lines in asecond position in which the movable member 50 is in the closedcondition to block the inflator vent opening 21 and permit fullinflation of the air bag 27.

A cap nut 60 is preferably threadably attached by internal threads 61 tothe threaded end portion 96 of the support member 88. Preferably, theinitiator device 80 is coupled to the cap nut 60 and extends partiallyinto a cap nut end opening 62 for connecting the initiator device 80 toan electrical source. The cap nut 60 secures the initiator 80 andplunger 70 to the support member 88 by sandwiching the end wall 18 ofthe housing 20 between the spacing shoulder 92 of the support member 88and a cap nut flange 63. In addition, the securement of the cap nut 60to the support member 88 attaches the support member 88 ,and thus theinflator 30, securely to the housing 20.

The shear feature 72 holds the plunger 70 and the movable member 50 in afirst initial position within the support member 88. It will beappreciated that in the first position, the slide portion 52 ispreferably not aligned with the inflator vent opening 21 on the housing20 such that the inflator vent opening 21 is preferably entirely openprior to activation of the inflator 30, as best shown in FIG. 1, forcontrolled reduction in inflation gas available for initial air baginflation. Upon activation of the initiator device 80, the plunger 70and movable member 50 coupled thereto are movable to a second positionin which the slide portion 52 on the movable member 50 is aligned withthe inflator vent opening 21 on the housing 20. Thus, when the movablemember 50 is in the second position, the inflator vent opening 21 isentirely closed such that all inflation gas is available for air baginflation, as described further hereinafter.

The initiator device 80 or squib preferably contains a chemical which isignited upon receiving a signal from vehicle sensors (not shown). A wire(not shown) transmits a signal from the sensors to the initiator device80 to activate the initiator device 80. Upon activation, the initiatordevice 80 produces a pressure wave that presses against the reactionsurface 74 of the plunger 70 and quickly forces the plunger 70 and themovable member 50 coupled to the plunger 70 from the first position tothe second position. Advantageously, the initiator device 80 produces apressure wave almost instantaneously and preferably within less than 1ms after activation. Thus, upon firing of the initiator device 80 themovable member 50 is moved from the first position in which the ventopenings 21 are entirely open to the second position in which the ventopenings 21 are entirely closed, almost instantaneously.

Referring to FIGS. 1 and 4, the variable inflation device assembly 49 isassembled as follows. The support member 88 is mounted on the headportion 32 of the inflator 30 and the plunger 70 is inserted into theaxial opening 89 of the support member 88 until the shear feature 72engages the support member 88 to limit further insertion. Next, the armportion 51 of the movable member 50 is inserted through the lower guidehole 94 and into the radial plunger hole 71 and out through the upperguide hole 93. The arm portion 51 is preferably attached to the plunger70 by the snap-fitted attachment feature 53. It will be appreciated thatduring activation, the guide holes 93, 94, guide the arm portion 51 tocontrol the movement of the movable member 50. Next, the initiatordevice 80 can be pressed into the cap nut end opening 62. Then theinitiator device 80 can be inserted into the plunger bore 73 and the capnut 60 can be screwed onto the threaded end portion 96 of the supportmember 88 to complete the variable inflation device assembly 49, asshown in FIG. 4.

If the module 10 is manufactured at the same location as the variableinflation device assembly 49, then the cap nut 60 need not be addeduntil after assembly of the inflator 30 to the housing 20. The variableinflation device assembly 49, minus the cap nut 60 and initiator device80, is inserted through the first end opening 22 of the housing 20 asenabled by the curved shape of the slide member 52. The threaded endportion 96 of the support member 88 is inserted through the second endopening 23 until the spacing shoulder 92 engages the end wall 18. Next,the cap nut 60 with the initiator device 80 therein can be screwed ontothe threaded end portion 96 of the support member 88 to secure thevariable inflation device assembly 49 to the housing 20.

Prior to activation of the inflator 30, the air bag 27 is stored in afolded condition atop the inflator 30. Also prior to activation of theinflator 30, the movable member 50 is held within the support member 88in the first position by the shear feature 72 with the slide portion 52misaligned with the inflator vent opening 21 such that the inflator ventopening 21 is open. Upon sensing certain predetermined vehicle andoccupant conditions, the sensors send a signal to the initiator device80 advising the initiator device 80 whether the movable member 50 shouldbe open or closed at a predetermined time during activation of theinflator 30 so that a certain amount of inflator gas is expelled outthrough the inflator vent opening 21. Referring to FIG. 3, if theinitiator device 80 is fired, the pressure wave or flame expelled by theinitiator device 80 reacts against the reaction surface 74 of theplunger 70 and instantaneously shoots the plunger 70 and movable member50 into the second position. The movement of the plunger 70 breaks offthe shear feature 72 such that the movable member 50 is nearlyinstantaneously shifted from the first position to the second position.When the movable member 50 is moved to the second position, the slideportion 52 is aligned with the inflator vent opening 21 such that theinflator vent opening 21 is entirely closed and inflator gas is blockedfrom expelling out the inflator vent openings 21.

Advantageously, certain predetermined inflator ports 31 are aligneddirectly with the inflator vent opening 21 such that the when themovable member 50 is in the first position, the inflator gas is expelleddirectly out through the inflator vent opening 21 and is never used toinflate the air bag 27. This is in contrast to typical vents like theside vent openings 24 which are designed to allow inflator gas to passover the side vent openings 24 and even enhance the inflation gasavailable by drawing in ambient air due to the Bernoulli effect duringair bag inflation. Then, the same side vent openings 24 can be usedafter fall air bag inflation to vent gas out during occupant ride down.Thus, the typical vent openings 24 of the prior art cannot providevariable inflation, but instead simply provide full air bag inflationand permit ride down venting.

By using the externally mounted device 49, the amount of inflator gasdischarged into the air bag 27 is variable to a wide range of levels,even with the use of the single stage inflator 30, as will now bedescribed. Upon the sensing of predetermined vehicle conditions bysensors (not shown), the inflator 30 is activated and receives thesignal to begin the process of discharging inflator gas at a time whichwill be designated as 0 milliseconds. It is noted that after theinflator 30 is activated, it may take an additional few millisecondsbefore the inflator gas actually begins to be discharged into the airbag 27. It will also be appreciated that the inflator gas is dischargedover a brief known period of total time for a given inflator 30 afteractivation. For example, after activation at 0 milliseconds, inflatorgas may be discharged until a total time of 60 milliseconds afteractivation. Of course, the amount of time that gas is discharged dependson the type of inflator 30 and is in no way limited to the example of 60milliseconds. Advantageously, the use of a initiator device 80 enablesthe inflator vent openings 21 to be either opened or closed almostinstantaneously upon firing of the initiator device 80. Thus, the amountof inflator gas discharged into the air bag 27 is easily varied bymoving the movable member 50 at a specific predetermined time as enabledby firing the initiator device 80.

The predetermined time for moving the movable member 50 is determined inresponse to predetermined conditions of the occupant and vehicle whichare sensed by one or more sensors and relayed to the initiator device80. The predetermined conditions preferably include the mass of theoccupant, the position of the occupant, the seat belt usage of theoccupant, and the amount and direction of vehicle deceleration. For agiven set of predetermined conditions at the time of inflatoractivation, a signal is sent to the initiator device 80 which tells theinitiator device 80 the predetermined time at which it should fire andmove the movable member 50 from the first position to the secondposition for those particular set of conditions. For example, theinitiator device 80 can be fired for moving the movable member 50 at atime of 10 ms into inflator activation or 20 ms into inflator activationor at any other time during inflator activation.

Thus, if the initiator device 80 is not fired, then the movable member50 remains in the first position and the inflator vent opening 21 isopen during the entire time of inflator gas discharge. Here, less thanthe full amount of inflator gas is then used to fill the air bag 27.Alternately, the initiator device 80 may be fired at the same time asinflator activation (time=0 ms) such that a predetermined minimum amountof inflator gas is expelled out through the vent opening 21 and themaximum amount of gas is used to fill the air bag 27. Thus, for eachmodule 10, a predetermined maximum amount of venting can be definedwhich is the maximum amount of venting that will occur if the ventopenings 21 are continuously open during the entire time of inflator gasdischarge. The maximum amount of venting for each module 10 is set to apredetermined percentage by the size and number of the vent openings 21on the housing 10.

Most preferably, the inflator vent opening 21 is directly aligned withcertain discharge ports 31 on the inflator 30 such that substantiallyall of the inflator gas discharged from the predetermined number ofdischarge ports 31 is expelled out through the corresponding alignedinflator vent opening 21 and is never available for air bag inflation.Advantageously, this allows the maximum amount of venting to be achievedwith the smallest and least amount of inflator vent openings 21possible. This may be desirable since the vent opening 21 can affect theride down characteristics of the air bag 27 after it is inflated. If thevent openings 21 are the smallest possible for the maximum amount ofventing, then deflation of the air bag 27 upon occupant interaction isthe least affected. Occupant ride down can be controlled in othermanners, such as by side vent openings 24 on the housing or by vents(not shown) on the air bag 27. Alternately, the inflator vent opening 21can also be tuned to a size that is desirable for occupant ride down aswell as maximum inflator gas discharge.

After determining the maximum percent of venting for the module 10 bysize and placement of the vent opening 21, any variation between themaximum amount of venting and the minimum amount of venting (typicallyzero venting) can be achieved by moving the movable member 50 at apredetermined time during inflator 30 activation.

This can be further understood with reference to FIG. 7. FIG. 7 showsthe generic inflation curves for a generic module having about 40%maximum venting. However, the general shape of the curves will be thesame for any amount of maximum venting. The curves represent the percentof maximum inflator output delivered to the air bag 27 versus time thatthe inflator 30 actually discharges gas in milliseconds for a genericmodule in which the vent opening 21 is normally open when the movablemember 50 is in the first position.

For example, curve a′ represents when the movable member 50 remains inthe first position during the entire inflator activation. Curve a′ showsthat when the vent opening 21 is never closed, only 60% of the inflatorgas output is delivered to the air bag 27 for inflation and 40% or themaximum amount is expelled out through the inflator vent opening 21 inthe housing 20. At the other end of the range, curve e′ shows thesituation in which the movable member 50 is moved to the second positionduring the entire inflator activation. Curve e′ shows that when the ventopening 21 is closed at 0 ms or approximately at the same moment thatthe inflator 30 is activated, then 100% of inflator output is deliveredto the air bag 27. It will be appreciated that the 40% maximum ventingwas a predetermined amount based on the size and location of the ventopening 21 and can be varied. Curve d′ depicts that when the movablemember 50 is moved to the second position at the predetermined time of20 ms into inflator 30 activation, then about 90% of the inflator gasoutput is delivered into the air bag 27 and 10% of the inflator gas isexpelled out through the vent opening 21. Curve c′ represents thescenario in which the movable member 50 is moved to the second positionat the predetermined time of 30 ms into inflator 30 activation such thatabout 80% of the inflator gas output is delivered into the air bag 27and 20% of the inflator gas is expelled out through the inflator ventopening 21. Finally, curve b′ represents the scenario in which themovable member 50 is moved to the second position at the predeterminedtime of 40 ms into inflator 30 activation such that about 70% of theinflator gas output is delivered into the air bag 27 and about 30% ofthe inflator gas is expelled out through the inflator vent opening 21.It will be appreciated that the curves are merely exemplary and thatmany other inflation variations are possible depending on the maximumamount of venting and the time at which the initiator device 80 is firedto move the movable member 50. It will be appreciated that the ventingcould be varied from 0% to 100% with the appropriate number of ventopenings 21.

Thus, it will be appreciated that variable levels of inflation of theair bag 27 can be achieved using a single inflator 30 having only asingle level of gas output in combination with at least one inflatorvent opening 21 that is preferably either entirely open or entirelyclosed at a predetermined time during discharge of inflator gas by amovable member 50 is response to activation of a initiator device 80.Almost instantaneous control of the movable member 50 is enabled by theuse of the initiator device 80 that reacts nearly instantaneously to thesignal received from the vehicle sensors. The initiator device 80 isexpendable since it only need be used once, if at all during thelifetime of the inflator 30. The initiator device 80 has beenadvantageously used to produce mechanical movement, instead of as atypical igniter. It will be appreciated that the movable member 50 needonly be moved once during the lifetime of the module 10, if at all, andthus the use of an expendable device 80 is possible. It will also beappreciated that this system provides a relatively simple, costeffective and lightweight solution to providing variable levels of airbag 27 inflation from a single level inflator 30. Advantageously, thevariable inflation device 49 may be added to a conventional inflator 30without modification to turn a traditional single stage inflator 30 intoa multi-level inflator, although the additional vehicle sensors wouldstill be needed for sensing the vehicle and occupant conditions. Alsoadvantageously, this invention uses expendable parts, which are onlymoved once, if at all, such that reliability over numerous cycles ofmovement is not a concern. Furthermore, the inflator vent opening 21 iseither entirely open or entirely closed such that the movable member 50can be quickly fired open. There is no careful movement of the movablemember 50 which is needed for partially opening or partially closing thevent openings 21.

It will be understood that a person skilled in the art may makemodifications to the preferred embodiment shown herein within the scopeand spirit of the claims. For example, although the inflator 30 ispreferably a single stage inflator, it is not limited to use with asingle stage inflator. The invention could also be used with adual-stage or multi-stage inflator if desired, but is not necessary toprovide variable inflation at nearly any level. Although only onemovable member 50, one vent opening 21, and one device 80 are shown itwill be appreciated that there could be additional devices 80, ventopenings 21 and movable members 50 on a given module 10. Although theinflator vent opening 21 is preferably shown in the bottom wall 16, itwill be appreciated that the inflator vent opening 21 could be locatedanywhere on the housing 20 as long as it is directly aligned withcertain ports 31 of the inflator 30.

Although the embodiment shows the movable member 50 opening the inflatorvent opening 21 in the first position prior to inflator activation andclosing the inflator vent opening 21 at a predetermined time when movedto the second position upon activation of the initiator device 80, itwill be appreciated that the movable member 50 may alternately close thevent opening 21 in the first position prior to inflator activation andopen the vent opening 21 at a predetermined time during inflatoractivation when moved to the second position upon firing of theinitiator device 80.

FIGS. 5 and 6 show an alternate embodiment of the invention which isgenerally similar to the embodiment of FIGS. 1-3 and which has the samedescriptions as above for the same components having the same numbers.The main difference in this embodiment is that the spacing shoulder 92from the embodiment of FIGS. 1-4 has been replaced by a spacing ring 92′which is slip-fitted over the support member 88 for positioning thesupport member relative to the housing 20.

Another alternate embodiment of the invention will now be described withreference to FIG. 8. The embodiment of FIG. 8 will be described usingsimilar references numerals increased by 100. In brief, the embodimentof FIG. 8 differs from the above embodiments in that the movable member150 is further integrated with the diffuser portion 133 of the inflator130.

Referring to FIG. 8, an air bag module 110 is mounted in a vehicle (notshown) for protection of a vehicle occupant (not shown). The module 110includes a housing 120, an inflatable air bag 127, and an inflator 130for generating gas to inflate the air bag 127. The module 110 furtherincludes a variable inflation device 149 which is mounted on theinflator 130 and is used to vary the amount of inflator gas availablefor air bag inflation and to mount the inflator 130 to the housing 120,as described in detail hereinafter.

The housing 120 includes opposing sides walls (not shown) joined by abottom wall 116 and opposing end walls 117, 118. The end wall 117includes an enlarged first end opening 122 for receiving the inflator130 and variable inflation device 149 therethrough during assembly. Inaddition, the other end wall 118 preferably includes a second endopening 123 which is smaller than the first end opening 122 for mountingthe components of the variable inflation device 149. The side walls 114,115 and end walls 117, 118 cooperatively define a housing opening 119through which the air bag 127 is deployed. The housing 120 furtherincludes one or more direct inflator vent openings 121 which arepreferably positioned in the bottom wall 116 of the inflator 130 andwhich are directly aligned with specific predetermined discharge ports131 in the bottom of the inflator 130.

As best shown in FIG. 8, the inflator 130 may be of any conventionalconstruction for generating inflator gas to inflate the air bag 127.Advantageously, the inflator 130 is preferably a single stage inflator130 which outputs inflator gas at a single level for inflating the airbag 127. The inflator 130 has a generally cylindrical body portion 136and is insertable through the first end opening 122 in the end wall 117for insertion within the housing 120. The inflator 130 also includes aplurality of discharge ports 131 which are preferably circumferentiallyspaced around a diffuser portion 133 of the inflator 130. Preferably,certain predetermined discharge ports 131 are generally in directalignment with the corresponding direct inflator vent openings 121 inthe bottom wall 116 of the housing 120. The inflator 130 includes afirst end 134 and an opposite second end 135 on which the diffuserportion 133 is located. The second end 135 of the inflator 130 includesa generally flat head portion 132 onto which the variable inflationdevice 149 can be attached and which also serves as a stop surface forthe movable member 150, as described further hereinafter. The second end135 of the inflator 130 is operatively connected to the housing 120 bythe variable inflation device 149, as described further hereinafter.

The air bag 127 may be of any conventional construction for inflatingupon the discharge of inflator gas. Upon activation of the inflator 130,the air bag 127 is filled with a predetermined amount of inflator gas asdictated by the variable inflation device 149 and deploys out throughthe housing opening 119 for protection of the vehicle occupant. Acushion retainer 128 sewn into a mouth portion 129 of the air bag 127may be utilized to attach the air bag 127 to a rim portion 126 of thehousing 120.

The variable inflation device 149 includes the movable member 150, asupport member 188, and an initiator device 180. The support member 188preferably has a hollow tubular shape. The support member 188 includesinterior walls 195 defining an axial opening 189 into which the movablemember 150 and the initiator device 180 can be inserted during assembly.The support member 188 includes a first support end 190 preferablyhaving flange portion 191 that is secured directly to the head portion132 of the diffuser portion 133 of the inflator 130 at the second end135. The flange portion 191 may be secured by any suitable method, suchas welding, and the support member 188 is preferably made of a metallicmaterial. The flange portion 191 includes a bent portion 198 that iswelded atop the head portion 132 of the diffuser portion 133 and hasstraight portion 99 that is attached to a side wall 137 of the diffuserportion 133. The support member 188 is sized about the same as thesecond end opening 123 of the housing 120 so that the support member 188is press fit into the second opening 123 of the housing 120 duringassembly. The support member 188 includes a cap opening 162 into whichthe initiator device 180 can be inserted by a press fit attachment.

As best shown in FIG. 8, the diffuser portion 133 includes a guide hole193 in the head portion 132. The guide hole 193 is positioned adjacentcertain predetermined ports 131 on the inside of the diffuser portion133. The guide hole 193 allows insertion of the movable member 150 toblock certain predetermined inflator ports 131 upon activation of theinitiator device 180, as described further hereinafter. The supportmember 188 may include an orientation feature for proper positioning ofthe support member 188 relative to the housing 120 and for properpositioning of the guide hole 193.

The variable inflation device 149 further includes the movable member150 which is preferably integrally formed from a plastic material andhas a generally cylindrical shape. The movable member 150 of thisembodiment also serves as the plunger, such that one component iseliminated and the movable member 150 is one piece with the formerplunger. The movable member 150 includes a plunger portion 170 and aslide portion 152. The movable member 150 is seated inside the supportmember 188 and preferably has a first end 176 that is suitably attachedto the initiator device 180, such as by adhesion or snap-fit. Themovable member 150 has a size smaller than the axial opening 189 suchthat the movable member 150 is slidable relative to the interior walls195 of the support member 188. Upon activation of the initiator device180, the plunger portion 170 and slide portion 152 slide within thesupport member 188 until the slide portion 152 engages the back diffuserwall 138 of the diffuser portion 133 which acts as a stop surface. Theplunger portion 170 also preferably includes an axial plunger bore 173in which the initiator device 180 is seated prior to activation. Areaction surface 174 of the plunger 170 is located in the bottom of theaxial bore 173. The movable member 150 may also include an orientationfeature for proper alignment of the slide portion 152 during assembly.

The slide portion 152 is preferably integrally formed with the plungerportion 170 in this embodiment to provide the movable member 150. Theslide portion 152 is generally planar and preferably follows thecurvature of the diffuser portion 133 and is shaped for being receivedinto the guide hole 193 on the diffuser portion 133. The movable member150 is movable relative to the inflator vent opening 121 and inflatorports 131 for opening and closing the inflator vent opening 121 at apredetermined time to control the amount of inflator gas discharged intothe air bag 127 and the amount of inflator gas expelled out through theinflator vent opening 121 of the housing 120. The slide portion 152 ofthe movable member 150 is vertically alignable between the inflator ventopening 21 and certain predetermined discharge ports 131. The movablemember 150 is shown in a first position in solid lines in which theinflator vent opening 121 is open for lowering the amount of gasavailable for air bag inflation. FIG. 8 shows the slide portion 152 inphantom lines in a second position in which the movable member 150 is inthe closed condition to block the inflator vent opening 121 and permitfall inflation of the air bag 127.

Securement of the wall portion 176 of the plunger portion 170 to theinitiator device 180 holds the movable member 150 in a first initialposition within the support member 188. It will be appreciated that inthe first position, the slide portion 152 is preferably not aligned withthe inflator vent opening 121 on the housing 120 such that the inflatorvent opening 121 is preferably entirely open prior to activation of theinflator 130 for controlled reduction in inflation gas available forinitial air bag inflation. Upon activation of the initiator device 180,the plunger portion 170 breaks away from the initiator device 180 by theforce of the initiator device 180 on the reaction surface 174 and themovable member 150 is movable to a second position in which the slideportion 152 is aligned with the inflator vent opening 121 on the housing120. Thus, when the movable member 150 is in the second position, theinflator vent opening 121 is entirely closed such that all inflation gasis available for air bag inflation.

The initiator device 180 or squib preferably contains a chemical whichis ignited upon receiving a signal from vehicle sensors (not shown). Awire (not shown) transmits a signal from the sensors to the initiatordevice 180 to activate the initiator device 180. Upon activation, theinitiator device 180 produces a pressure wave that presses against thereaction surface 174 of the plunger portion 170 and quickly forces themovable member 150 from the first position to the second position.Advantageously, the initiator device 180 produces a pressure wave almostinstantaneously and preferably within less than 1 ms after activation.Thus, upon firing of the initiator device 180 the movable member 150 ismoved from the first position in which the vent openings 121 areentirely open to the second position in which the vent openings 121 areentirely closed, almost instantaneously.

Advantageously, certain predetermined inflator ports 131 are aligneddirectly with the inflator vent opening 121 such that the when themovable member 150 is in the first position, the inflator gas isexpelled directly out through the inflator vent opening 121 and is neverused to inflate the air bag 127.

By using the variable inflation device 149, the amount of inflator gasdischarged into the air bag 127 is variable to a wide range of levels,even with the use of the single stage inflator 130, as described abovewith regard to FIGS. 1-3 and 7.

It will be understood that a person skilled in the art may makemodifications to the preferred embodiment shown herein within the scopeand spirit of the claims. For example, although the inflator 130 ispreferably a single stage inflator, it is not limited to use with asingle stage inflator. The invention could also be used with adual-stage or multi-stage inflator if desired, but is not necessary toprovide variable inflation at nearly any level. Although only onemovable member 150, one inflator vent opening 121, and one initiatordevice 180 are shown it will be appreciated that there could beadditional initiator devices 180, inflator vent openings 121 and movablemembers 150 on a given module 110. Although the inflator vent opening121 is preferably shown in the bottom wall 116, it will be appreciatedthat the inflator vent opening 121 could be located anywhere on thehousing 120 as long as it is directly aligned with certain ports 131 ofthe inflator 130.

Although the embodiment shows the movable member 150 opening theinflator vent opening 121 in the first position prior to inflatoractivation and closing the inflator vent opening 121 at a predeterminedtime when moved to the second position upon activation of the initiatordevice 180, it will be appreciated that the movable member 150 mayalternately close the vent opening 121 in the first position prior toinflator activation and open the vent opening 121 at a predeterminedtime during inflator activation when moved to the second position uponfiring of the initiator device 180.

While the present invention has been described as carried out inspecific embodiments hereof, it is not intended to be limited therebybut is intended to cover the invention broadly within the scope andspirit of the appended claims.

What is claimed is:
 1. An air bag module for restraint of an occupant ina vehicle, the air bag module comprising: an air bag; an inflator beingactivatable to discharge inflator gas for inflating the air bag, theinflator having at least one discharge port through which inflator gasis discharged; a housing including at least one inflator vent openingaligned with the discharge port; and a variable inflation device mountedon the inflator, the variable inflation device including a movablemember alignable with the vent opening, the movable member being movablerelative to the vent opening for opening and closing the vent opening ata predetermined time during inflator activation to control the amount ofinflator gas discharged into the air bag and the amount of inflator gasexpelled out through the vent opening of the housing.
 2. The module ofclaim 1 wherein the variable inflation device extends between theinflator and housing and mounts an end of the inflator to the housing.3. The air bag module of claim 2 wherein the variable inflation deviceincludes a moveable member slidably mounted on a support member.
 4. Theair bag module of claim 1 wherein the variable inflation device includesa support member extending between the inflator and housing, the supportmember mounting an end of the inflator to the housing.
 5. The air bagmodule of claim 4 wherein the variable inflation device includes amoveable member slidably mounted on the support member.
 6. The air bagmodule of claim 5 wherein the movable member is positioned in a firstposition for opening the vent opening such that at least a portion ofthe inflator gas is normally expelled out through the vent opening andwherein the movable member is movable to a second position for closingthe vent opening at a predetermined time during activation of theinflator to increase the amount of inflator gas discharged into the airbag.
 7. A variable inflation device for use with an air bag modulehaving a housing and an inflatable cushion, comprising: an inflatorhaving at least one discharge port through which an inflator gas isdischargable, said inflator being mountable in the housing such thatsaid at least one discharge port is alignable with at least one ventopening of the housing; means for connecting said inflator to thehousing, and defining a cavity; a movable member being movably mountedwithin said cavity and being movable relative to said discharge port todirect an inflating amount of said inflation gas to the inflatablecushion and to direct a vented amount of said inflator gas away from theinflatable cushion through said vent opening; and an initiator beingdisposed in said cavity and being activatable to move said movablemember.
 8. The variable inflation device of claim 7, wherein saidmovable member comprises: a driving portion, said driving portion havinga reaction surface being adapted to receive a pressure wave from saidinitiator; and a driven portion, said driven portion being adapted todirect said inflating amount and said vented amount of said inflatorgas.
 9. The variable inflation device of claim 8, wherein said drivingportion is integrally formed with said driven portion.
 10. The variableinflation device of claim 7, wherein said movable member is movable froman initial open position to a second closed position to direct saidinflating amount and said vented amount of said inflator gas.
 11. Avariable inflation device for use with an air bag module having ahousing and an inflatable cushion, comprising: an inflator having atleast one discharge port through witch an inflator gas is dischargable,said inflator being mountable in the housing such that said at least onedischarge port is alignable with at least one vent opening of thehousing; means for connecting said inflator to the housing, and defininga cavity, wherein said means for connecting comprises: a support memberdepending outwardly from said inflator and having a support portion anda threaded portion, said support portion being adjacent said inflatorand said threaded portion being distant from said inflator; and a nut,said nut being adapted to threadably engage said threaded portion, saidsupport portion including a shoulder, said shoulder being abutable withan interior surface of the housing such that said threaded portionextends from the housing for receiving said nut; and a movable memberbeing movably mounted within said cavity and being movable relative tosaid discharge port to direct an inflating amount of said inflation gasto the inflatable cushion and to direct a vented amount of said inflatorgas away from the inflatable cushion through said vent opening; and aninitiator being disposed in said cavity and being activatable to movesaid moveable member.
 12. A variable inflation device for use with anair bag module having a housing and an inflatable cushion, comprising:an inflator having at least one discharge port through which an inflatorgas is dischargable, said inflator being mountable in the housing suchthat said at least one discharge port is alignable with at least onevent opening of the housing; means for connecting said inflator to thehousing, and defining a cavity, wherein said means for connectingcomprises: a support member extending from said inflator, said supportmember being adapted to form a press fit connection with an opening ofthe housing such that a portion of said support member abuts an interiorsurface of the housing; a movable member being movably mounted withinsaid cavity and being movable relative to said discharge port to directan inflating amount of said inflation gas to the inflatable cushion andto direct a vented amount of said inflator gas away from the inflatablecushion through said vent opening; and an initiator being disposed insaid cavity and being activatable to move said movable member.
 13. Anair bag module for use in a vehicle, comprising: an inflatable cushion;an inflator being activatable to discharge an inflation gas forinflating said inflatable cushion, said inflator having at least onedischarge port through which said inflation gas is discharged; a housingincluding at least one inflator vent opening, said inflator vent openingbeing fluidly aligned with said at least one discharge port; aninitiator being activatable to discharge a pressure wave; a drivingmember, said driving member having a reaction surface being adapted toreceive said pressure wave from said initiator; and a driven memberbeing movable by said driving member to a position between saiddischarge port and said vent opening at a predetermined time duringactivation of said inflator to diffuse an inflating portion of saidinflator gas into said inflatable cushion and to diffuse a ventedportion of inflator gas out of said housing through said vent opening.14. The air bag module of claim 13, wherein said driving member is aplunger and said driven member is a slide portion.
 15. The air bagmodule of claim 14, wherein said plunger is integrally formed with saidslide portion.
 16. The air bag module of claim 13, further comprising:means for connecting said inflator to said air bag housing, said meansfor connecting defining a cavity, said cavity being adapted to receivesaid initiator, said driving member and said driven member.
 17. The airbag module of claim 13, wherein said driving member is integrally formedwith said driven member.
 18. An air bag module for use in a vehicle,comprising: an inflatable cushion; an inflator being activatable todischarge an inflation gas for inflating said inflatable cushion, saidinflator having at least one discharge port through which said inflationgas is discharged; a housing including at least one inflator ventopening, said inflator vent opening being fluidly aligned with said atleast one discharge port; an initiator being activatable to discharge apressure wave; a driving member, said driving member having a reactionsurface being adapted to receive said pressure wave from said initiator;and a driven member being movable by said driving member to a positionbetween said discharge port and said vent opening at a predeterminedtime during activation of said inflator to diffuse an inflating portionof said inflator gas into said inflatable cushion and to diffuse avented portion of inflator gas out of said housing through said ventopening; and means for connecting said inflator to said air bag housing,said means for connecting defining a cavity, said cavity being adaptedto receive said initiator, said driving member and said driven memberand said means for connecting comprises: a support member having asupport portion and a threaded portion, said support portion beingadjacent said inflator and said threaded portion being distant from saidinflator; and a cap nut, said cap nut being adapted to threadably engagesaid threaded portion, said support portion including a shoulder, saidshoulder being abutable with an interior surface or said housing suchthat said threaded portion extends from said housing for receiving saidcap nut.
 19. An air bag module for use in a vehicle, comprising: aninflatable cushion; an inflator being activatable to discharge aninflation gas for inflating said inflatable cushion, said inflatorhaving at least one discharge port through which said inflation gas isdischarged; a housing including at least one inflator vent opening, saidinflator vent opening being fluidly aligned with said at least onedischarge port; an initiator being activatable to discharge a pressurewave; a driving member, said driving member having a reaction surfacebeing adapted to receive said pressure wave from said initiator; and adriven member being movable by said driving member to a position betweensaid discharge port and said vent opening at a predetermined time duringactivation of said inflator to diffuse an inflating portion or saidinflator gas into said inflatable cushion and to diffuse a ventedportion of inflator gas out of said housing through said vent opening;and means for connecting said inflator to said air bag housing, saidmeans for connecting defining a cavity, said cavity being adapted toreceive said initiator, said driving member and said driven member andsaid means for connecting comprises: a support member extending fromsaid inflator, said support member being adapted to form a press fitconnection with an opening of said housing with a portion of saidsupport member abutting with an interior surface of said housing.